I suffer with this dreadfully to the point when I finish a ride I'm already weeing blood and its straight onto the antibiotics that I keep for this reason! I have however found that damage limitation consists of crucially drinking lots. A wee mid cycle will flush out any nasties but most importantly of all, wash your Betty and slather in an antibacterial barrier cream. I use sudocrem or that moo stuff although a little thin. Also apply to padding. Have a big drink on your return and wash Betty ASAP! It's the bane of my life. I'm sat here suffering now instead of cycling because I didn't do the above! We are all different anatomically. Leaking wee, sweat and bacteria from our skin has a party in our shorts while we cycle and the cystitis is the hangover!